Residual Capacity Research Articles

Damage mechanism and assessment of precast double-column bridge piers under blast impact

This paper aims to investigate the damage mechanism of precast double-column bridge piers under blast impact and propose a new damage evaluation method. The three-dimensional solid separation model of a pier column under explosion actions is established using ANSYS/LS-DYNA, and the accuracy of the numerical simulation method is verified by the existing experimental results. Subsequently, numerical experiments of the double-column bridge piers under explosions are carried out. The damage accumulation process and local failure mechanism are investigated with the analyses of the propagation of stress waves in concrete. In addition, the criteria containing residual bearing capacity and local damage are introduced in the damage assessment, aiming to evaluate the explosion damage degree of bridge piers comprehensively. The P-I (pressure-impulse) curves of precast double-column piers are established, based on the overpressure-impulse damage assessment method by Henrych’s empirical formula. The general evaluation process and method of double-column bridge piers under blast impacts are proposed and verified. The research results provide important insights and references for the anti-blast design of precast double-column piers and their bridge systems.

Dynamic changes in lung water density and volume following supine body positioning.

Measure the changes in relative lung water density (rLWD), lung volume, and total lung water content as a function of time after supine body positioning. An efficient ultrashort-TE pulse sequence with a yarnball k-space trajectory was used to measure water density-weighted lung images for 25 min following supine body positioning (free breathing, 74-s acquisitions, 3D images at functional residual capacity, 18 time points) in 9 healthy volunteers. Global and regional (10 chest-to-back positions) rLWD, lung volume, and total lung water volume were measured in all subjects at all time points. Volume changes were validated with a nitrogen washout study in 3 participants. Global rLWD increased significantly (p = 0.001) from 31.8 ± 5.5% to 34.8 ± 6.8%, while lung volumes decreased significantly (p < 0.001) from 2390 ± 620 mL to 2130 ± 630 mL over the same 25-min interval. Total lung water volume decreased slightly from 730 ± 125 mL to 706 ± 126 mL (p = 0.028). There was a significant chest-to-back gradient in rLWD (20.7 ± 4.6% to 39.9 ± 6.1%) at all time points with absolute increases of 1.8 ± 1.2% at the chest and 5.4 ± 1.9% at the back. Nitrogen washout studies yielded a similar reduction in lung volume (12.5 ± 0.9%) and time course following supine positioning. Lung volumes during tidal breathing decrease significantly over tens of minutes following supine body positioning, with corresponding increases in lung water density (9.2 ± 4.4% relative increase). The total volume of lung water is slightly reduced over this interval (3.3 ± 4.0% relative change). Evaluation of rLWD should take time after supine positioning, and more generally, all sources of lung volume changes should be taken into consideration to avoid significant bias.

Relationships between wood properties and fire performance of glulam columns made from six wood species commonly used in China

Glued laminated timber stands as an increasingly favored engineered wood product in low-rise modern timber structures due to its commendable structural performance and carbon sequestration potential. Chinese standards presently fail to differentiate the effects of distinct wood species on the fire resistance of glulam. This study examined the charring rate and residual bearing capacity of glulam columns made from six commonly used wood species in China: poplar, Chinese fir, Douglas fir, hemlock, larch, and spruce. These materials exhibited densities ranging between 390 and 645 kg·m−³. ISO standard fire tests were conducted employing one- and two-adjacent-side fire exposures. Notably, the findings unveiled that high-density glulam columns demonstrated lower charring rates and slower rates of heat penetration. The two-adjacent-side fire configuration induced a corner effect, consequently amplifying the effective charring depth. The results showed a linear relationship between the ratio of diagonal to horizontal charring rate of the columns exposed to the two-adjacent-side fire and wood density. To enhance practical application, a formula was developed, employing the residual section method, to calculate the column's residual bearing capacity post two-adjacent-side fire exposure. This formula incorporates an adjustment depth to accommodate the corner effect, effectively mitigating the reduced wood strength within the pyrolysis zone.

Modelling Policy Pathways to Maximise Renewable Energy Growth and Investment in the Democratic Republic of the Congo Using OSeMOSYS (Open Source Energy Modelling System)

This study sought to generate, evaluate, and recommend possible national policies for the government of the Democratic Republic of the Congo (DRC) to implement to most effectively boost growth and investment in renewable energy technologies (RETs) through 2065 using Open Source Energy Modelling System (OSeMOSYS). The novelty of this study stems in-part from the scarcity of RET modelling completed for specific West African countries rather than for broader regions. Market-based instruments were identified as the policy type most practical for DRC. From modelling the resulting energy systems for policy pathways involving a 16% RET subsidy, a 70% fossil fuel tax, and both in combination relative to no-policy baseline scenarios, the scenarios including the tax had the lowest net costs (USD304–306 B) and the highest proportion of RETs (above 90%). Additionally, despite the current reliance on hydropower to fulfil 98% of its energy needs, hydropower played a very minor role in all of a modelled scenarios (no future investment beyond residual capacity). Finally, a post-modelling market potential assessment was performed on the technology that dominated off-grid supply across policy pathways: a 0.3 kW small solar home system (SHS). Based on learning rates for solar photovoltaics (PV), demand for a small SHS in DRC (&gt;160 million units in total) was found to be sufficient to substantially reduce the unit cost as deployment scales. Ultimately, this study yielded four recommendations for the DRC government: (1) Pursue financial incentives to catalyse DRC’s renewable energy supply. (2) Tax fossil fuel energy production. (3) Re-evaluate focus on hydropower. (4) Promote DRC as a healthy market for solar home systems.

Influence of thermal strain on concrete spalling

Understanding the susceptibility to spalling of concrete members in case of fire is important to evaluate the residual load-bearing capacity. The investigations of the spalling phenomenon of a concrete mixture using real scale members are necessary but expensive to carry out. Reducing the specimen size leads to an increase of boundary effects that can result in a reduced spalling or absence of spalling. In this study, fire tests were carried out on unrestrained, single-sided exposed, cuboid shaped specimens (0.6 m ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document} 0.6 m ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document} 0.29 m) as well as unrestrained and steel ring restrained cylindrical specimens (Ø = 0.47 m, h = 0.29 m), which induce different boundary conditions. These fire tests were carried out on two ordinary concrete mixtures. The two mixtures differ only in the type of aggregates (quartz gravel and basalt grit) and were used to investigate the influence of the thermal expansion of the aggregate on the spalling behaviour of the concrete. The results show a significant increase of the spalling depth due to the restrained thermal expansion achieved by the applied steel rings. Additionally, the type of aggregate has a direct influence on the spalling behaviour of a concrete mixture. The reduction of the boundary effects by the steel rings recreate the test conditions in the centre of a large concrete member. Thus, this type of specimen is suitable to determine the susceptibility to spalling of a material (screening-tests) as preliminary investigations to full scale fire tests.

Experimental and theoretical investigation on residual bearing capacity of CFDST-T joints after lateral impact

This study investigates the residual performance of concrete-filled double-skin steel tubular (CFDST) T-joints after lateral impact. One hollow T-joint and five CFDST-T joints with various steel tube thickness and hollow rate were first tested by a pendulum machine. The axial compression test was subsequently performed to explore the residual performance in terms of failure mode, residual bearing capacity, ductility, energy dissipation, and strain evolution. Results indicated that the failure modes of the CFDST-T joint and hollow T-joint were characterized by global bending and severe local indentation, respectively. Besides, the CFDST-T joints exhibited the strongest residual bearing capacity with a hollow rate of 0.52 and the greatest ductility of 0.63. Moreover, increasing the outer tube thickness improved the residual bearing capacity and simultaneously reduced the ductility coefficient while the inner tube exerted little effect on residual performance. Simplified calculation formulas were finally derived to predict the impact residual deflection and residual bearing capacity of the CFDST-T joint based on parametric analysis. This study will provide a reference for future research to contribute to the design of more reasonable CFDST-T joints and promote their application.

Experimental investigation on residual capacity of steel-reinforced concrete-filled thin-walled steel tubular columns subjected to combined loading and temperature

Steel-reinforced concrete-filled thin-walled steel tube (SRCFST) is gaining popularity in construction, primarily due to its superior structural performance. However, there is still a scarcity of studies investigating the residual capacity of SRCFST columns subjected to a full-range fire. A comprehensive research was conducted in this, involving both experimental testing and numerical simulation, to investigate the residual capacity of SRCFST columns. Six SRCFST columns were tested under combined loading and temperature to achieve the temperature distribution, failure modes, residual strength, and structural response within the cross-section. The developed finite element (FE) model was used to validate the test results. Three different paths, including after exposure to fire and without initial load, the full-range fire, and the actual path in the current test, were considered toevaluate the influence of different time-load-temperature paths on the mechanical properties of SRCFST columns. Results reveal that the region comprised of profiled steel and surrounded concrete forms a composite constrained region, with little loss of strength and stiffness occurring in the core region. The initial load level and heating time ratio were found to have a significant negative influence on the residual load-carrying capacity and ductility of SRCFST columns. In contrast, circular SRCFST columns are more resistant to the effects of fire than square SRCFST columns. Finally, the existing design methods were used and extended to evaluate the residual load-carrying capacity of SRCFST columns subjected to a complete temperature-load-time process.

Lung Ultrasound Assessment of Lung Hyperinflation in Patients with Stable COPD: An Effective Diagnostic Tool.

To evaluate the degree of lung hyperinflation (LH) in patients with stable chronic obstructive pulmonary disease (COPD) by lung ultrasound score (LUS) and assess its value. We conducted a study of 149 patients with stable COPD and 100 healthy controls recruited by the Second Affiliated Hospital of Fujian Medical University. The pleural sliding displacement (PSD) was measured, the sliding of the pleura in different areas was observed, and LUS was calculated from both of them. The diaphragm excursion (DE), residual capacity (RV), total lung capacity (TLC), inspiratory capacity (IC) and functional residual capacity (FRC) were measured. We described the correlation between ultrasound indicators and pulmonary function indicators reflecting LH. Multiple linear regression analysis was used. The ROC curves of LUS and DE were drawn to evaluate their diagnostic efficacy, and De Long method was used for comparison. (1) The LUS of patients with stable COPD were positively correlated with RV, TLC, RV/TLC and FRC and negatively correlated with IC and IC/TLC (r1=0.72, r2=0.41, r3=0.72, r4=0.70, r5=-0.56, r6=-0.65, P < 0.001). The correlation was stronger than that between DE at maximal deep inspiration and the corresponding pulmonary function indices (r1=-0.41, r2=-0.26, r3=-0.40, r4=-0.43, r5=0.30, r6=0.37, P < 0.001). (2) Multiple linear regression analysis showed that LUS were significantly correlated with IC/TLC and RV/TLC. (3) With IC/TLC<25% and RV/TLC>60% as the diagnostic criterion of severe LH, the areas under the ROC curves of LUS and DE at maximal deep inspiration for diagnosing severe LH were 0.914 and 0.385, 0.845 and 0.543, respectively (P < 0.001). The lung ultrasound score is an important parameter for evaluating LH. LUS is better than DE at maximal deep inspiration for diagnosing severe LH and is expected to become an effective auxiliary tool for evaluating LH.

Modelling of fire behavior of RC girders strengthened by external prestressing

Since the 1950s, external post-tensioning has been a powerful tool for retrofitting existing bridges. In unbonded prestressing, the post-tensioning tendons are positioned outside the concrete cross-section, and the prestressing forces are transferred to the girder through end anchorages, deviators, or saddles. This implies that these could be critical elements for the bridge performance against fire. This paper examines reinforced concrete bridges strengthened by external prestressing and subjected to fire, using a mixed experimental and analytical approach. Initially, load tests are conducted on a model of a bridge beam strengthened by external prestressing to assess the effectiveness of the intervention until failure. The ultimate limit state (ULS) capacity of the beam is then evaluated both before and after rehabilitation. Subsequently, the fire performance is investigated through different scenarios defined by the fire load curves of Eurocode, evaluating the cross-sectional temperatures resulting from fire, estimating the loss of external prestressing efficiency, and assessing the beam’s overall fire resistance. This methodology is then applied to a real girder bridge with adjacent beams of the same type, extending the approach used on the experimental scaled beam to an actual bridge deck. Results are presented in terms of performance levels for different traffic load values and residual capacity over time from fire ignition, providing a safety assessment of girder bridges under fire exposure. The procedure is straightforward and immediately applicable to many existing reinforced bridges. The findings demonstrate how quickly external prestressing degrades, leaving the beam unprotected, and highlight the fundamental importance of the protective sheath for external tendons in limiting this degradation. Evaluating load levels based on exposure time also allows engineers to estimate the service time before rescue arrives, given the expected traffic level.

Monitoring the filling of the landfill using the results of aerial photography

The important task of landfill current residual capacity assessment was solved in this work. The modern methods of high-precision three-dimensional reconstruction were used by the results of unmanned aerial vehicle survey, equipped with a global navigation satellite system receiver. The main stages of work were combining the project and field survey data into one coordinate and height system, reconstruction of designed underground and above-ground parts of landfill, project and actual model comparison, the calculation. As a result, the estimation of the landfill residual capacity becomes possible, which allows to develop recommendations for further landfill operation. The proposed approach allows rapid and high-quality active monitoring of the engineered facility. Photogrammetric processing of the results of low-altitude aerial photography makes it possible to obtain objective data on the current actual state of the landfills, to carry out competent and valid management of the landfill functioning. Such studies can significantly extend the landfill’s lifetime, minimize the negative impact on the environment and predict the attainment of projected capacity much more accurately.

SPECT/CT to quantify early small airway disease and its relationship to clinical symptoms in smokers with normal lung function: a pilot study.

Smokers frequently display respiratory symptoms despite the fact that their pulmonary function tests (PFTs) can be normal. Quantitative lung ventilation single-photon emission computed tomography (SPECT/CT) can provide a quantification of lung ventilatory homogeneity and could prove useful as an early marker of airway disease in smokers. We measured the effects of smoking on regional ventilation distribution in subjects with normal lung function and evaluated whether ventilation distribution in these subjects is related to lung function tests results and clinical symptoms. Subjects without any history of respiratory disease were prospectively recruited and separated in two groups: active smokers (AS: ≥10 cigarettes/day and history of ≥15 pack-years) and never smokers (NS: lifetime exposure of <5 cigarettes). All subjects performed PFTs (which had to be normal, defined as z-score values of forced expiratory volume in 1s (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, total lung capacity (TLC) residual volume and diffusion capacity (DLCO) all falling between -1.65 and +1.65) and underwent SPECT/CT with Technegas, which generated subject- specific ventilation heterogeneity maps. The area under the compensated coefficient of variation (CV) density curve for CV values > 40%, (AUC-CV40%) was used as the measure of ventilation heterogeneity. 30 subjects were recruited (15 per group). Subjects in the AS group displayed higher dyspnea levels (1 [1-2] vs. 0 [0-1] units on mMRC scale, p < 0.001). AUC- CV40% was significantly higher in the AS group (0.386 ± 0.106 vs. 0.293 ± 0.069, p = 0.004). AUC-CV40% was significantly correlated to FEV1 (rho = -0.47, p = 0.009), DLCO (rho = -0.49, p = 0.006), CAT score (rho = 0.55, p = 0.002) and mMRC score (rho = 0.54, p = 0.002). Subjects with mMRC >0 had higher AUC-CV40% values than those without dyspnea (0.289 ± 0.071 vs. 0.378 ± 0.102, p = 0.006), while FEV1 and DLCO were not different between those groups. ROC analyses showed that the AUC for AUC-CV40% in identifying subjects with mMRC score >0 was 0.78 (95%CI 0.61-0.95, p = 0.009), which was significantly higher than that of FEV1 and DLCO. In smokers with normal lung function, ventilatory inhomogeneities can be quantified using SPECT/CT. AUC-CV40% values are related to lung function decline and to respiratory symptomatology, suggesting a potential role for this marker in the evaluation of symptomatic smokers.

Activation strategies for glass-to-iron-based shape memory alloy adhesively bonded joints

Previous research has demonstrated the potential of improving the performance of glass beams through pre-stressed bonded iron-based shape memory alloy (Fe-SMA) tendons. The pre-stressing of bonded Fe-SMA tendons significantly enhanced both the initial glass cracking load and the residual load-bearing capacity of glass beams, compared with unstrengthened ones. To achieve the desired pre-stress level, the Fe-SMA should be activated, which involves controlled heating and natural cooling of the Fe-SMA. The achieved pre-stress level of the substrates highly depends on the activation strategies for the Fe-SMA, such as activation position, length and temperature. An appropriate activation strategy is essential to achieve a high pre-stress level and to prevent premature failures, such as glass breakage or debonding during activation. This experimental work was carried out on glass-to-Fe-SMA bonded joints. Two activation temperatures (160 ºC and 200 ºC) were considered, aiming to attain high pre-stress levels while avoiding glass breakage and debonding. Afterwards, the effect of service temperature (50 ºC and 80 ºC) on the pre-stress loss was investigated. The findings in this research contribute to the efficient design and application of pres-stressing glass elements using adhesively bonded Fe-SMA tendons.

Safety assessment of a CFRP retrofitted bridge

The maintenance of existing bridges sometimes requires an intervention to increase their residual bearing capacity during their service life. The bridge strengthening can modify significantly the original structural behaviour, but, in many cases, the lack of a specialized standard for existing structures in the past prevented the designer to operate a suitable check of the updated performance. In the paper, an example of a three-span overpass, built in the sixties in Lombardia, is investigated. Around ten years ago a significant restoration was carried out due to the bad conditions of the infrastructure: the P/C beams were retrofitted by means of CFRP strips and the top slab over the two internal piers was also strengthened by additional reinforcement. After a basic diagnostic aimed at verifying the mechanical characteristics declared in the documentation attached to the drawings and the pictures of the retrofitting intervention, a load test driven by a preventive structural analysis carried out by means of a linear elastic approach allowed to fix a control procedure aimed at guaranteeing the safety conditions in the future time. The discussion on the adopted procedure is the main goal of the paper.

Efficacy observation of erythropoietin on sepsis complicated with acute respiratory distress syndrome

This study is to evaluate the efficacy of erythropoietin in treating sepsis-associated acute respiratory distress syndrome (ARDS). One hundred patients with sepsis-related ARDS were randomized into the placebo group and Erythropoietin (EPO) group. Patients in the placebo group received saline as placebo on the standard therapy, while the EPO group received recombinant human erythropoietin injections on the standard therapy. It was found that the heart rate and mean arterial pressure did not differ significantly between days 7 and 14 after treatment initiation (p &gt; 0.05). The partial pressure of oxygen (PaO2) and oxygenation index levels measured on days 7 and 14 were significantly higher than the placebo group and partial pressure of carbon dioxide (PaCO2) was significantly lower than the placebo group (p &lt; 0.05). Lung capacity and functional residual capacity (and FRC) increased significantly in tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), and C-reactive protein (CRP) concentrations (p &lt; 0.05). In the EPO group, the duration of mechanical ventilation was significantly shorter and the mortality rate was significantly reduced (Log-Rank test, χ2 = 4.651, p = 0.031). The results confirm that EPO significantly improves lung function and blood gas parameters, reduces serum levels of inflammatory markers, and reduces the risk of death in sepsis-induced ARDS patients, highlighting the potential therapeutic role of EPO in the management of this disease.

Anesthetic dilemmas in an achondroplastic patient undergoing elective cesarean section.

Achondroplasia is a genetic condition characterized by skeletal dysplasia that results in characteristic craniofacial and spinal abnormalities. It is the most common form of short-limbed skeletal dysplasia. Additionally, a pregnant patient who is morbidly obese warrants specific anatomical and physiological considerations, such as a difficult airway with potential hypoxia, full stomach precautions, and a reduced functional residual capacity. Achondroplasia increases the risks of maternal and fetal complications. Although neuraxial techniques are generally preferred for cesarean sections, there is no consensus among patients with achondroplasia. We aimed to discuss the anesthetic challenges in an achondroplastic patient and report our regional anesthesia approach for an elective cesarean section.

АДАПТАЦИЯ РЕСПИРАТОРНОЙ СИСТЕМЫ ЧЕЛОВЕКА В УСЛОВИЯХ СЕВЕРНОГО РЕГИОНА К НИЗКОТЕМПЕРАТУРНЫМ ФАКТОРАМ

The article reviews scientific publications on the human respiratory system’s adaptation to low temperature factors in the northern regions of Russia. It is shown that cold, as a pulmonotropic factor, has a significant impact on the human respiratory system, leading to modifications in the respiratory system intended to reduce the trauma caused by prolonged exposure to low temperatures. The present findings show that there is a decrease in maximum voluntary ventilation and forced vital capacity of the lungs with a concomitant increase in residual volume and functional residual capacity of the lungs throughout the process of human respiratory system adapting to the North environment.

A Decentralized Nonlinear Harmonic Power Sharing Scheme Considering Harmonic Residual Capacity and Working Conditions of Fundamental Load

A Decentralized Nonlinear Harmonic Power Sharing Scheme Considering Harmonic Residual Capacity and Working Conditions of Fundamental Load

Obezbeđivanje disajnog puta novorođenčadi i odojčadi - preporuke

Tracheal intubation is one of the most frequently performed medical procedures in neonatal intensive care units. Younger children, pre-term and full-term infants are at the highest risk of respiratory and traumatic complications when securing the airway. A difficult airway implies a clinical situation in which difficult airway management occurs by an experienced specialist. It is recommended to apply an adequate depth of sedation or general anesthesia with muscle relaxation in neonates and infants during the airway management in order to ensure the comfort and safety of the patients. The use of a videolaryngoscope with standard blades (Macintosh and Miller) is recommended for securing the airway, especially in neonates and infants. Use of passive oxygenation during tracheal intubation prolongs the safe duration of apnea, increases functional residual capacity and reduces the incidence of hypoxemia. The use of supraglottic airway device for rescue ventilation and oxygenation is advised if tracheal intubation has failed and ventilation with a face mask is inadequate. Limiting the number of tracheal intubation attempts is recommended. If two or fewer laryngoscopies are unsuccessful, operator should switch to indirect methods for intubation. After four attempts, intubators should stop and wake the child. It is advised to immediately check the position of the tube simultaneously with clinical signs and the appearance of sustainable carbon dioxide curve. Assessment of clinical indicators is necessary to predict successful awake extubation. A tidal volume greater than 5 ml/kg may indicate readiness for extubation.

Progressive Collapse Resistance Assessment of a Multi-Column Frame Tube Structure with an Assembled Truss Beam Composite Floor under Different Column Removal Conditions

To estimate the progressive collapse resistance capacity of a multi-column frame tube structure with an assembled truss beam composite floor (ATBCF), pushdown analysis and nonlinear dynamic analysis are conducted for such a structure using the alternate load path (ALP) method. The bearing capacities of the remaining structures under three different work conditions, which are the side middle column removal, the edge middle column removal, and the corner column removal, are individually studied, and the collapse mechanism of the remaining structures is analyzed based on the aspects of the internal force redistribution and the failure mode of the second defense line. Simultaneously, the influence of the column failure time on the dynamic response of the remaining structure and the dynamic amplification coefficient is discussed. The results indicate that the residual bearing capacity of the remaining structure following the bottom corner column removal is higher than that of the one following the side or edge middle column removal, while the latter has a stronger plastic deformation capacity. When the ALP method is adopted to operate the progressive collapse analysis, it is reasonable to take the column failure time as 0.1 times the period of the first-order vertical vibration mode of the remaining structure, and it is suitable to set the dynamic amplification coefficient as 2.0, which is the ratio of the maximum dynamic displacement to the static displacement of the remaining structure under the transient loading condition.

Residual bearing capacity of concrete-filled double-skin steel tube K-joints after lateral impact

With the application of jacket offshore wind turbines (OWT), the jackets are exposed to the risk of ship collision. However, concrete-filled double-skin steel tube K-joints (CFDST-K joints) in the jacket can still operate normally after slight impacts. To study the residual axial properties of the joints, eight CFDST-K joints and one hollow K-joint were tested by a long column testing machine, focusing on the failure mode, residual bearing capacity, displacement, and ductility after impact. Results indicated that the typical failure mode of the joints was characterized by overall bending resulting from excessive midspan deflection. The residual properties were negatively correlated with the initial damage. Specifically, the stiffness degradation was worsened as the impact energy and axial compression ratio increased, causing an evident decrease in residual bearing capacity and ductility. Moreover, increasing the outer tube thickness improved the bearing capacity by enhancing the confinement effect of the steel tube on the concrete. Furthermore, the hollow ratio exerted a great effect on ductility. A calculation method for the original loading capacity of CFDST-K joints was also proposed, and the damage index was introduced to assess the damage degree. The results verified that the joints still possessed excellent bearing capacity after impact.